Check battery health in Settings
The fastest way to see your iPhone battery's condition is through the built-in Battery Health tool. Open Settings, tap Battery, then Battery Health & Charging. You will see a percentage labeled Maximum Capacity — this shows how much charge your battery can hold compared to when it was new.
A new iPhone battery is at 100 percent. After normal use over months or years, this number drops. At 80 percent capacity, your battery still works but holds less charge per full cycle. Most people notice a real difference in daily battery life once capacity falls below 80 percent. If your maximum capacity is below 50 percent, the battery is significantly degraded.
The same screen also shows Charging Optimization Status. If it says "Optimized Battery Charging is on," your iPhone is learning your charging habits and may slow charging to 80 percent overnight to extend battery lifespan. This is normal and intentional.
Key Takeaways
- Maximum Capacity in Battery Health shows what percentage of the original charge your battery can still hold, and dropping below 80 percent usually means noticeably shorter daily battery life.
- Condition status tells you whether your battery is Normal, Degraded, or needs Service, with Service meaning Apple recommends replacement.
- Peak Performance Capability explains whether your phone will slow down under heavy load to protect the battery, which happens only on older batteries.
- You can also run a diagnostic test through Apple Support or visit an Apple Store to get a full battery report with more technical details.
Understand the Condition status
Below Maximum Capacity, you will see a line labeled Condition. This tells you whether your battery is working normally or showing signs of wear. Normal means the battery is healthy and does not need attention. Degraded Battery Health means capacity has dropped enough that Apple recommends you think about replacement, though the battery still works.
If the status says Service Recommended, Apple has detected a problem — either the battery cannot hold charge properly or it is swelling. Do not ignore this. A swollen battery can damage the phone and poses a safety risk. Contact Apple Support or visit an Apple Store to arrange a replacement. Most iPhones with Service Recommended status are still under warranty or covered by AppleCare+.
The Condition status is the most important number on this screen. If it says Normal, your battery is fine even if Maximum Capacity is at 85 percent. If it says Service Recommended, capacity percentage does not matter — replacement is the right move.
Check Peak Performance Capability
The third section on the Battery Health screen is Peak Performance Capability. This explains whether your iPhone will slow itself down under heavy use. On a new battery, your phone runs at full speed all the time. On an older or degraded battery, iOS may reduce processor speed during demanding tasks to avoid unexpected shutdowns.
If Peak Performance Capability says your phone is running at full speed, the battery is healthy enough that slowdowns are not needed. If it says your iPhone has reduced peak performance, the battery is weak enough that the phone throttles itself to stay stable. You will notice this as lag during gaming, video editing, or other intensive work.
Throttling is a protection feature, not a defect. It keeps your phone from shutting down mid-task. But if you use your iPhone for demanding work and throttling bothers you, battery replacement will restore full speed.
Run a diagnostic test through Apple Support
If you want more detail than the Settings screen provides, you can request a battery diagnostic. Open Settings, tap General, then About. Scroll down and look for Diagnostics. If you see an option to share diagnostics with Apple, tap it and follow the prompts. This sends a technical report to Apple's servers.
You can also visit an Apple Store and ask a technician to run a battery test. They have hardware tools that measure voltage, charge cycles, and internal resistance — data the Settings app does not show. The test takes a few minutes and is free. If the battery needs replacement, they can usually do it the same day or within a few days depending on stock.
A diagnostic test is worth doing if your phone is shutting down unexpectedly, if the battery drains much faster than it used to, or if you want a professional opinion before paying for replacement.
Monitor battery drain over a few days
Beyond the Battery Health screen, you can watch how fast your battery drains during normal use. Open Settings, tap Battery, then Battery Usage. This shows which apps have used the most battery power over the last 24 hours or the last 10 days. Tap the time period toggle at the top to switch between them.
If one app is using far more battery than others — say, 40 percent of your daily drain — that app may be the problem, not the battery itself. Close it or uninstall it and see if battery life improves. If battery drains evenly across many apps, or if drain is heavy even when you are barely using the phone, the battery itself is likely degraded.
Track your battery percentage at the same time each day for a week. If a full charge used to last until evening and now it lasts until noon, your battery capacity has dropped noticeably. This real-world test often tells you more than the percentage in Battery Health, because it shows how the battery performs under your actual usage pattern.
Know when to replace the battery
Replace your iPhone battery if the Condition status says Service Recommended, if Maximum Capacity has dropped below 50 percent, or if daily battery life has become too short for your needs. You do not have to wait for the battery to fail completely.
Battery replacement costs vary by iPhone model and whether you have AppleCare+. Without AppleCare+, expect to pay between $50 and $100 at an Apple Store. With AppleCare+, battery replacement is usually covered at no cost if the battery is defective. Third-party repair shops often charge less, but Apple batteries come with a one-year warranty and are may provide to be genuine.
If your iPhone is old enough that the battery is failing, consider whether the phone itself still meets your needs. A five-year-old iPhone with a new battery will still be a five-year-old phone. If you are replacing the battery on a phone you plan to keep for another two or three years, replacement makes sense. If the phone is nearing the end of its useful life anyway, a new battery may not be worth the cost.
Frequently Asked Questions
What is a normal battery capacity percentage for an older iPhone?
After one year of normal use, most iPhones are at 95 to 98 percent capacity. After two years, 90 to 95 percent is typical. After three years, 85 to 90 percent. These numbers vary based on how often you charge, whether you let the battery drain to zero, and how hot your phone gets. If your iPhone is two years old and already below 80 percent, you are using it more intensively than average.
Does turning off Optimized Battery Charging make the battery last longer?
No. Optimized Battery Charging slows charging to 80 percent overnight to reduce wear on the battery. Turning it off lets your phone charge to 100 percent faster, but the battery will degrade more quickly over time. If you want maximum battery lifespan, leave it on. If you need a full charge by morning, you can turn it off temporarily.
Can I test my battery without going to Apple?
The Battery Health screen in Settings is the most reliable test you can run yourself. Third-party battery testing apps exist, but they cannot access the same internal data that Apple's tools can. If you want a professional diagnosis, an Apple Store test is free and takes minutes. Third-party repair shops can also test batteries, but results may vary in accuracy.
What does it mean if my iPhone shuts down even though the battery percentage is high?
This usually means the battery cannot deliver power fast enough under load, even though it still holds charge. It is a sign of significant degradation. Check the Battery Health screen — if Condition says Service Recommended or if Maximum Capacity is very low, the battery needs replacement. Unexpected shutdowns are not normal and should not be ignored.
Is it safe to keep using an iPhone with degraded battery health?
A degraded battery that shows Normal condition is safe to use. A battery that shows Service Recommended status should be replaced soon, especially if it is swollen or causing shutdowns. A swollen battery can damage the phone's internal components and poses a small fire risk, so do not delay replacement in that case.